A dual Olympic silver medallist who pressed almost 20,000 party pills he thought were legal and bungled attempts to cook methamphetamine has been jailed for more than two years.

Former kayaker Nathan Baggaley, whose career unravelled in 2005 when he was banned for taking steroids, stood emotionless at Sydney's District Court this afternoon as he and younger brother Dru Baggaley were punished for manufacturing drugs.

The Baggaley brothers had both earlier pleaded guilty to producing more than 18,000 2CB tablets in 2013 and conspiring to make about 100g of ice.

The court heard the duo didn't realise 2CB was outlawed soon after they started making it, and never ended up selling the drugs so didn't turn a profit.

Judge Leonie Flannery said it was also clear their bid to manufacture methamphetamine by cooking pseudoephedrine had failed.

Judge Flannery said she thought the brothers displayed good prospects of rehabilitation, were unlikely to reoffend and had shown genuine remorse.

However, she said the pair were "high-level" participants in a plot to make the marketable quantities of 2CB and ice.